This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing charge enhancing additives, which impart or assist in imparting a negative charge to the toner particles and enable toners with rapid triboelectric charging characteristics. In embodiments, there are provided in accordance with the present invention toner compositions comprised of a polymer or polymer resins, pigment particles or dye molecules, and manganese complex charge enhancing additives obtained, for example, by the reaction of a manganese salt, such as manganese chloride or manganese sulfate, with an aikylsalicylic acid, and preferably di-tertiary-butylsalicylic acid. In embodiments, the present invention is directed to toners with manganese complexes of di-tertiary-alkyl, especially butylsalicylic acid charge enhancing additives. The aforementioned charge additives, in embodiments of the present invention enable, for example, toners with rapid admix, and stable triboelectric charging characteristics. Advantages associated with the charge additives of the present invention include their low cost, they are environmentally safe, minimal or no adverse impact on the melt index of certain toner resins like crosslinked SPAR.TM. polyesters, and the like. The aforementioned toner compositions usually contain a colorant component comprised of, for example, carbon black, magnetites, or mixtures thereof; color pigments or dyes such as cyan, magenta, yellow, blue, green, red, brown, or mixtures thereof thereby providing for the development and generation of black and/or colored images. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes, including color processes, discharge area development (DAD), charged area development (CAD), hybrid scavengeless development, inductive magnetic brush, conductive magnetic brush, single component magnetic brush, and agitated zone development processes as illustrated in U.S. Pat. No. 4,368,970 (D/79176QI) or U.S. Pat. No. 4,394,429, the disclosures of which are totally incorporated herein by reference.
Toners with negative charge additives are known, reference for example U.S. Pat. Nos. 4,411,974 and 4,206,064, the disclosures of which are totally incorporated herein by reference. The '974 patent discloses negatively charged toner compositions comprised of resins, pigment particles, and as a charge enhancing additive ortho-halophenyl carboxylic acids. Similarly, there are disclosed in the '064 patent toner compositions with chromium, cobalt, and nickel complexes of salicylic acid as negative charge enhancing additives. In U.S. Pat. No. 4,845,003, there are illustrated negatively charged toners with certain aluminum complex charge additives. More specifically, this patent discloses as charge additives aluminum complexes comprised of two or three hydroxybenzoic acid ligands bonded to a central aluminum ion. Disadvantages of some of these charge additives is their thermal instability, that is they often break down or decompose during the thermal extrusion process of the toner manufacturing cycle, and these additives can cause crosslinking in certain resins, thus toners with these additives can possess undesirable admix characteristics. Another disadvantage is that some of these additives are colored, which can render them unsuitable for use in nonblack toners, and also a number of these additives can be considered toxic in certain areas of the United States. A fast rate of triboelectric charging is particularly crucial for high speed xerographic machines since, for example, these machines consume toner rapidly, and fresh toner has to be constantly added. The added uncharged toners, therefore, must charge up to their equilibrium triboelectric charge level rapidly to ensure no interruption in the xerographic imaging or printing operation. Many of these and other disadvantages are eliminated, or substantially eliminated with the metal complex charge additives of the present invention.
Developer compositions with charge enhancing additives, which impart a positive charge to the toner particles, are also known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of quaternary ammonium salts as charge control agents for electrostatic toner compositions; 4,221,856 which discloses electrophotographic toners containing resin compatible quaternary ammonium compounds in which at least two R radicals are hydrocarbons having from 8 to about 22 carbon atoms, and each other R is a hydrogen or hydrocarbon radical with from 1 to about 8 carbon atoms, and A is an anion, for example sulfate, sulfonate, nitrate, borate, chlorate, and the halogens such as iodide, chloride and bromide, reference the Abstract of the Disclosure and column 3; a similar teaching is presented in U.S. Pat. No. 4,312,933, which is a division of U.S. Pat. No. 4,291,111; similar teachings are presented in U.S. Pat. No. 4,291,112 wherein A is an anion including, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens; U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, illustrates developer compositions containing as charge enhancing additives organic sulfate and sulfonates, which additives can impart a positive charge to the toner composition; and U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, illustrates positively charged toner compositions with resins and pigment particles, and as charge enhancing additives alkyl pyridinium compounds.
Illustrated in U.S. Pat. No. 5,275,900 are toner compositions comprised of polymer resins, colorants comprised of color pigment particles or dye molecules, and certain metal complex charge additives derived from the reaction of a mixture of a hydroxybenzoic acid and a base with a metal ion in the presence of an excess of a hydroxyphenyl. More specifically, this copending application illustrates a negatively charged toner composition comprised of polymer, colorant, optional surface additives, and a metal complex charge enhancing additive of the following formula ##STR1## where M is a metal; N+ is a cation; R and R' are alkyl, alkoxy, aryloxy, halogen, carbonyl, amino, nitro, or mixtures thereof; m and n are the number of R substituents ranging from 0 to 3; y- is the magnitude of the negative charge of the anion; and y' represents the number of cations.
Illustrated in U.S. Pat. No. 5,309,387 is a negatively charged toner composition comprised of a polymer or polymers, pigment, and a metal complex charge enhancing additive as essentially represented by the following formula ##STR2## where M is the central metal ion; N+ is the countercation; R and R' are selected from the group consisting of alkyl, alkoxy, aryloxy, halogen, carbonyl group, alkoxycarbonyl group, amino group, nitro group or mixtures thereof; m and n are the number of R substituents on the aromatic rings, ranging from 0 to 3; y- is the magnitude of the negative charge of the anion or the number of the countercations of the metal complex, and represents the number 1 or 2; and y' represents the number of countercations N+; U.S. Ser. No. 964,544 (D/92402) discloses a toner composition comprised of a polymer or polymers, pigment particles and/or dyes, optional surface additives, and a charge enhancing additive of the following formula ##STR3## wherein R is hydrogen, alkyd, or aryl; R' and R" are selected from the group consisting of alkyl, alkoxy, aryl, and aryloxy; R'" is selected from the group consisting of alkyl, alkoxy, oxide, and halide; M is boron or a metal; x is a number of from 1 to 4; and y is a number of from 0 to 2; and U.S. Pat. No. 5,290,651 discloses a negatively charged toner composition comprised of polymer, pigment, optional surface additives, and a zinc complex charge enhancing additive represented by either of the two following formulas ##STR4## wherein R, R', R", and R'" are independently selected from the group consisting of hydrogen, alkyl, aryl alkoxy, aryloxy, halogen, amino, and hydroxy. The disclosures of each of the aforementioned copending applications are totally incorporated herein by reference.
Illustrated in U.S. Pat. No. 5,250,381, the disclosure of which is totally incorporated herein by reference, is a negatively charged toner composition comprised of resin particles, pigment particles, and an aluminum salt of thiophenecarboxylic acid charge enhancing additive, and a negatively charged toner composition comprised of resin, pigment, and an aluminum salt charge enhancing additive of the following formula ##STR5##
While a number of charge enhancing additives are known, there continues to be a need for charge enhancing additives which enable toners with many of the advantages illustrated herein. There is also a need for negative charge enhancing additives which are useful for incorporation into black and colored toner compositions which can be utilized for developing positively charged electrostatic latent images. Moreover, there is a need for colored toner compositions containing charge enhancing additives which do not interfere with the color quality of the colorants present in the toners. Another need relates to the provision of toner compositions with certain charge enhancing additives, which toners in embodiments thereof possess substantially stable triboelectric charge levels, and display acceptable rates of triboelectric charging characteristics. Furthermore, there is also a need for toner compositions with certain charge enhancing additives which possess excellent dispersibility characteristics in toner resins, and can, therefore, form stable dispersions in the toner compositions. There is also a need for negatively charged black and colored toner compositions that are useful for incorporation into various imaging processes, inclusive of color xerography, as illustrated in U.S. Pat. No. 4,078,929, the disclosure of which is totally incorporated herein by reference; laser printers; and additionally a need for toner compositions useful in imaging apparatuses having incorporated therein layered photoresponsive imaging members, such as the members illustrated in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Also, there is a need for negatively charged toner compositions which have desirable triboelectric charge levels of, for example, from between about -10 to about -40 microcoulombs per gram, and preferably from about -15 to about -25 microcoulombs per gram, and triboelectric charging rates of less than about 120 seconds, and preferably from about 30 to about 60 seconds as measured by standard charge spectrograph methods or when the toners are frictionally charged against suitable carrier particles via conventional roll milling techniques. There is also a need for charge additives that are economical, and that are considered nontoxic. The amount of the charge additives that can be selected for the toner compositions of the present invention generally range from about 0.05 weight percent to about 10 weight percent, depending on whether the charge additive is utilized as a surface additive or as a dispersion in the bulk of the toner. The effective amount of toner in the developer, that is toner and carrier particles, is, for example, from about 0.5 to about 10 weight percent, and preferably from about 1 to about 5 weight percent.